Thursday, February 23, 2006

Incommensurate Worldviews

AUTHOR: Allen MacNeill

SOURCE: Original essay

COMMENTARY: That's up to you...

I am beginning to understand more about the differences between the physical sciences (such as astronomy, chemistry, and physics) and the biological sciences, and why the worldview of a physical scientist with a strongly mathematical predilection is apparently so different from mine and that of most other biologists (at least, of those biologists of whom I have personal and/or reputable knowledge). Furthermore, it seems to me that these differences are central to the apparent inability of non-biologists to fully comprehend the "darwinian" worldview upon which much of biology (and all of evolutionary theory) has been constructed (and vice versa, of course).

To me, these appear to be the basic differences that inform our worldviews:

1) CONTINGENCY: The biological sciences (i.e. anatomy & physiology, parts of biochemistry, botany, development & embryology, ecology, ethology, evolution, genetics, marine biology, neurobiology, and the allied subdisciplines), like the "earth sciences" (i.e. atmospheric sciences, geology, etc.) are both contingent and historical. That is, they cannot be derived from "first principles" in the way that algebra, calculus, geometry (both euclidean and non-euclidean), probability, symbolic logic, topology, trigonometry, and other "non-empirical" sciences can be. As both Ernst Mayr and Karl Popper have pointed out, historical contingency is inextricably intertwined with biological causation, in a way that it is not in mathematics and the physical sciences. This would appear to be true, by the way, for both "darwinist" and ID models of biological evolution and the fields derived from them. Indeed, even the Judeo-Christian-Muslim worldview is contingent and historical, in ways antithetical to both mathematics and pre-"big bang" cosmological physics.

2) UNIVERSALITY: The biological sciences are also not "universal" in the way that chemistry and physics are. We assume that the processes described by physical "laws" are universal and ahistorical. that is, we assume that they are the same regardless of where, when, and by whom they are investigated. Furthermore, it is tacitly assumed by physical scientists that the "laws" they discover apply everywhere and everywhen, without empirical verification that this is, in fact, the case. It seems to me that this assumption is reinforced by the mathematical precision with which physical processes can be analyzed and described.

By contrast, the entities and processes studied by biologists are necessarily "messy" and often "non-quantifiable," in the sense that they cannot be entirely reduced to purely mathematical abstractions. The great beauty and elegance of Newton's physics and Pauling's chemistry are that the objects and processes they describe can be so reduced, and when they are, they reveal an underlying mathematical regularity, a regularity so precise and so elegant that one is tempted to believe that the mathematical formalism is what is "real" and the physical entities and processes that they describe are, at best, somewhat imperfect expressions of the underlying perfect regularities.

To me, however, what has always been appealing about biology is its very "messiness." As the so-called Law of Experimental Psychology states "Under carefully controlled conditions, the organism does whatever it damn well pleases." Biological entities and processes are not quantifiable in the same way that physical ones are. This is probably due to the immensely greater complexity of biological entities and processes, in which causal mechanisms are tangled and often auto-catalytic.

3) STOCHASTICITY: The biological sciences are irreducibly statistical/stochastic, in ways that neither the physical nor mathematical sciences generally are (although they are becoming moreso as they intrude deeper into biology). R. A. Fisher was not only the premier mathematical modeler of evolution, he was also the founder of modern statistical biometry. This is no accident: both field and laboratory biology (but not 19th century natural history) depend almost completely on statistical analysis. Again, this is probably because the underlying causes for biological processes are so multifarious and intertwined.

Physicists, chemists, and astronomers can accept hypotheses at confidence levels that biologists can never aspire to. Indeed, until recently the whole idea of "confidence levels" was generally outside the vocabulary of the physical sciences. When you repeatedly drop a rock and measure its acceleration, the measurements you get are so precise and fit so well with Newton's descriptive formalism that the idea that one would necessarily need to statistically verify that they do not depart significantly from predictions derived from that formalism seems superfluous. Slight deviations from the predicted behavior of non-living falling objects are considered to be just that: deviations (and most likely the result of observer error, rather than actual deviant causation). Rarely does any physical scientist look at such deviations as indicative of some new, perhaps deeper formalism (but consider, of course, Einstein's explanation of the precession of the orbit of Mercury, which did not fit Newton's predictions).

4) FORMALIZATION: There are many processes in biology, and especially in organismal (i.e. "skin out" biology) that are so resistant to quantification or mathematical formalization that there is the nagging suspicion that they cannot in principle be so quantified or formalized. It is, of course, logically impossible to "prove" a negative assertion like this - after all, our inability to produce a Seldonian "psychohistory" that perfectly formalizes and therefore predicts animal (and human) behavior could simply be the result of a deficiency in our mathematics or our ability to measure and separately analyze all causative factors.

However, my own experience as a field and laboratory biologist (I used to study field voles - Microtus pennsylvanicus - and now I study people) has instilled in me what could be called "Haldane's Suspicion:" that biology "is not only queerer than we imagine, but queerer than we can imagine." That is, given the complexity and interlocking nature of biological causation, it may be literally impossible to convert biology into a mathematically formal science like astronomy, chemistry, or physics.

But that's one of the main reasons I love biology so much. Mathematical formalisms, to me, may be elegant, but they are also sterile. The more perfect the formalism, the more boring and unproductive it seems to me. The physicists' quest for a single unifying "law of everything" is apparently very exciting to people who are enamored of mathematical formalism for its own sake. But to me, it is the very multifariousness – one could even say "cussedness" – of biological organisms and processes that makes them interesting to me. That biology may not have a single, mathematical "grand unifying theory" (yes, evolution isn't it ;-)) means to me that there will always be a place for people like me, who marvel at the individuality, peculiarity, and outright weirdness of life and living things.

5) PLATONIC VS. DARWINIAN WORLDVIEWS: It seems to me that many ID theorists come at science from what could be called a "platonic" approach. That is, a philosophical approach that assumes a priori that platonic "ideal forms" exist and are the basis for all natural forms and processes. To a person with this worldview, mathematics are the most "perfect" of the sciences, as they literally deal only with platonic ideal forms. Astronomy, chemistry, and physics are only slightly less "prefect," as the objects and processes they describe can be reduced to purely mathematical formalisms (without stochastic elements, at least at the macroscopic level), and when they are so reduced, the predictive precision of such formalisms increases, rather than decreases.

By contrast, I come at science from what could be called a "darwinian" approach. Darwin's most revolutionary (and subversive) idea was not natural selection. Indeed, the idea had already been suggested by Edward Blythe. Rather, Darwin's most "dangerous" idea was that the variations between individual organisms (and, by extension, between different biological events) were irreducibly "real." As Ernst Mayr has pointed out, this kind of "population thinking" fundamentally violates platonic idealism, and therefore represents a revolutionary break with mainstream western philosophical traditions.

I am and have always been partial to the "individualist" philosophical stance represented by darwinian variation. It informs everything I think about reality, from the idea that every individual living organism is irreducibly unique to the idea that my life (and, by extension, everybody else's) is irreducibly unique (and non-replicible). Such a philosophical position might seem to lead to a kind of radical "loneliness," and indeed there have been times when that was the case for me. But since all of us are equal in our "aloneness," it paradoxically becomes one of the things we universally share.

And so, I don't think a "darwinian worldview" applies to the physical sciences (and certainly does not apply to non-empirical sciences, such as mathematics), for the reasons I have detailed above. In particular, it seems clear to me that although it may be possible to mathematically model microevolutionary processes (as R. A. Fisher and J. B. S. Haldane first did back in the early 20th century), it is almost certainly impossible to mathematically model macroevolutionary processes. The reason for this impossibility is that macroevolutionary processes are necessarily contingent on non-repeatable (i.e. "historical") events, such as asteroid collisions, volcanic eruptions, sea level alterations, and other large-scale ecological changes, plus the occurrence (or non-occurrence) of particular (and especially major) genetic changes in evolving phylogenies. While it may be possible to model what happens after such an event (e.g. adaptive radiation), the interactions between events such as these are fundamentally unpredictable, and therefore cannot be incorporated in prospective mathematical models of macroevolutionary changes.

It's like that famous cartoon by Sidney Harris: "Then a miracle occurs..." The kinds of events that are often correlated with major macroevolutionary changes (such as mass extinctions and subsequent adaptive radiations) are like miracles, in that they are unpredictable and unrepeatable, and therefore can't be integrated into mathematical models that require monotonically changing dynamical systems (like newtonian mechanics, for example).

So, to sum up, I believe that the "darwinian worldview" applies only to those natural sciences that are both contingent and intrinsically historical, such as biology, geology, and parts of astrophysics/cosmology. Does this make such sciences less "valid" than the non-historical (i.e. physical) sciences? Not at all; given that physical laws now appear to critically depend on historical/unrepeatable events such as the "big bang," it may turn out to be the other way around. In the long run, even the physical sciences may have to be reinterpreted as depending on contingent/historical events, leaving the non-empirical sciences (mathematics and metaphysics) as the only "universal" (i.e. non-contingent/ahistorical) sciences.

To summarize it in a bullet point:

• Platonic/physical scientists describe reality with equations, whereas darwinian/biological scientists describe reality with narratives.


P.S. Alert readers may recognize some of the hallmarks of the so-called Apollonian vs. Dionysian dichotomy in the preceding analysis. That such characteristics are recognizable in my analysis is not necessarily an accident.

P.P.S. It is also very important to keep in mind, when considering any analysis of this sort, that sweeping generalizations are always wrong ;-)

Labels: , , , , , , , , , , , ,


At 2/23/2006 04:45:00 PM, Anonymous Anonymous said...

Interesting distinctions between physical and biological sciences.

But I see some mistakes and I don't find the distinctions so severe that you make them, which I believe you acknowledge in your last paragraph.

Contingency and universality. There must be a confusion here between contingency and emergence. Emergent phenomena may not be entirely derived from first principles. But first principles, or nearly so, physics may be contingent. In string physics and infinite inflation, physics laws in each universe may be contingent on the particular bigbang, which you mention in the last paragraph. By the same token they aren't universal.

Stochasticity. You have forgotten about chaos and the irreducible stochastics it introduces even in large scale physics.

Formalisation. It seems to me you don't acknowledge the productivity and richness that follows from even simple formal theories. Mathematicians certainly doesn't feel their areas being sterile.

Platonic worldview. This is, as you say, probably an ID characteristic. I don't think many scientists subscribe to that view.

When you make the distinction about "individualist" science, it's much more obvious. Not that physics can't have individual objects (see infinite inflation universes above, or astronomy), but it's not a common part by any means.

Last, I wouldn't characterise mathematics and metaphysics as sciences per se.

So I think that you are on to something interesting, but that your conclusion is the really incontrovertible part.

At 2/26/2006 06:37:00 PM, Anonymous Anonymous said...

You make reference to "ID models." I am curious as to what models you refer. The ID position is regularly criticized for its lack of distinctive models.

At 4/15/2006 10:49:00 PM, Anonymous Anonymous said...

Math: I'm surprised that you refer to math as 'non empirical science'. Since by the usual usage math is not science, why muddy the waters? Your statement that certain things are derived from first principles could be stated uncontroversially as: What is derived from axioms is derived from axioms. "First principles"? Take a look at the axioms of set theory:

This and the rather non trivial problem of arriving at suitable axioms (axioms which do what is desired without obvious contradictions) may give some insight into why the axioms are called axioms, not first principles.
Proof from axioms? Mathematicians in other branches of math than set theory suppose that their theorems could be derived from the basic axioms somehow, *by someone else*. They aren't about to try it themselves. Just ask them.

Physics: There is no good theory of such an everyday macroscopic matter as friction. The "laws" are based on experiments in the usual way. That is, you test various implications of the laws. What can you prove? I once had a physics prof explain things very well including the experimental basis of Newton's laws, including the third law although he didn't give much detail on that one. A couple week later he startled me by announcing that ""This proposition" is proved by pure mathematics. It does not require experiments at all". The proof was based largely on the third law. I was so taken aback by this reverse reasoning that I didn't say anything at the time. However, the proposition, being an implication of the third law, was just the sort of thing that had to be tested experimentally to justify the third law in the first place. This left me with the thought that perhaps physicists really do believe they prove things. However, the standard rule applies: a hypothesis is tested by way of its implications.
Something else was mentioned recently in another blog: when the going gets tough, the physicist gets going. In other words, when you can't easily do something with a mathematical mode, don't call it physics. Call it geology or meteorology, or biology,.... Thus what is left is the easy stuff.

Chemistry: hardly a computational subject. Don't you recall organic chemistry? All those stories -- a nucleophile "attacks", so the electrons go up there, but then they come back down and the designated leaving group leaves etc etc etc. Yeah right. Try computing that. And indeed, many of the reaction mechanisms are inferred (but not completely or certainly) from experiments -- not derived from 'first principles'.

Biology: you know there is lots of math in ecology and evolution. And you know that just as in other branches of science, this provides no exemption from the need for observation and experiment.

All the sciences test hypotheses by way of their implications, and can make good use of mathematical models at times.

Conclusion: I'm not so sure of your thesis of different kinds of sciences.


Post a Comment

<< Home